Robert Miller: Life below the ice

Updated 7:16 pm, Friday, February 8, 2013

Ice starts from the edges of a lake -- where the water is cold -- then moves toward the middle.

Small lakes get the big chill first. But with a sustained few weeks of cold, even a big lake like Candlewood Lake, which holds more water -- and hence, more warm water -- starts to yield to the season.

Under the ice, life -- while slow -- continues at a different pace. Some fish get a little torpid. Some turtles burrow into the mud and let their life systems slow to a crawl.

For the benefit of a great variety of species -- including fish who swim and humans who skate -- water has an odd property.

First, as it cools, it gets more dense and heavier.

But only up to a point. When water gets colder than 39 degrees, it begins to reverse that process and becomes lighter. At 32 degrees, when it freezes, it's lighter still -- a solid that's lighter than a liquid.

That's why ice in a drink floats. It's why ice doesn't sink to the bottom of a lake and crush everything underneath it.

In the days leading up to winter, water in lakes begins circulating. The colder water starts sinking, displacing warmer water, which rises to the surface, gets colder and sinks in turn.

Eventually, the really cold water -- at freezing or just below that -- stays on top. The water of about 39 degrees stays at the bottom.

Machowski said other fish -- like bass -- still swim around and continue to feed but they slow down. They eat enough to survive, but unlike warm-blooded Christmas cookie-eating humans, they don't grow or put on weight in winter.

Pinou said some turtles bury themselves in the mud at the bottom of a lake. Others crawl onto land when the cold comes and find burrows in dry ground.

"Loose soil and leaf litter contains a lot of air," she said. "Air is a great insulator."

But here is the good news. When spring comes, the process is reversed. The ice melts, plants start growing, the fish start moving. Turtle hearts start beating faster.